(Note: Last in a series previewing the Buffs position-by-position during training camp. Today: Defensive line.)

BOULDER - Mike Tuiasosopo firmly believes that good defenses are constructed from the inside out, which explains why he was mystified a couple of springs ago when he first stepped onto the practice field to coach Colorado's defensive interior.

Tuiasosopo's top returning tackle - junior Will Pericak - desperately needed a supersized dose of fundamentals. And Tuiasosopo's position as a whole cried out for a major infusion of real life-sized D-linemen.

That last part of "Tui's" to-do list - replenishing his roster with size and strength - was accomplished in February when CU signed a school-record nine defensive linemen in its Class of 2012.

The first part - a major makeover for Pericak - might have been easier than winning all those recruiting battles. That's because Pericak simply wanted to become a better football player - and in Tuiasosopo's opinion Pericak has gone beyond that.

"He's a solid starter," Tuiasosopo said. "I don't know what other teams have in this conference in terms of interior guys. I do know about the Star Lotulelei kid at Utah, but Will certainly in my eyes can be in that conversation about the best interior guys in this conference."

Strong words from his coach, but the 6-4, 285-pound Pericak feels strongly about backing them up. He called his two-year improvement "night and day . . . my play has definitely gotten better. But it's probably going to show up more this season than last season."

Pericak's progress literally came from the ground up - where to position his hand, what to do with his feet, how to use his leverage . . . you name it and Pericak needed to learn it, then sharpen it.

"When the new coaching staff came in I had the fundamentals of the last staff, which weren't really like . . . great," he recalled. "It was nothing like I've gotten from 'Tui' and Kanavis (McGhee, DE/OLB coach). With the new coaches coming in, there was a whole new 'how to play,' a whole new technique, really a whole new everything. It took me awhile to pick it up, but now that you have it you just keep building off it. I've gotten the fundamentals down and kept expanding my knowledge."

Choosing his words carefully, "Tui" remembered when he arrived, CU's returning D-linemen "didn't know our way of teaching defensive linemen, coaching them up. It was just a hard concept for (Pericak) to grasp - to the very root of everything, hand placement, understanding what one-gap defense was. It was like, to be honest, a foreign language to a lot of these guys - Will included."

Pericak described his first spring under the new coaching staff "definitely a rough one," and Tuiasosopo added, "People don't realize it, but he lost his job in my first spring here. If you'll remember, it was Conrad Obi and Curtis Cunningham . . . and part of it was because (Pericak) just couldn't figure it out.

"I've always said 'knowledge is power.' I have that (posted) in the back of my meeting room. To be a great defensive player you've got to be very, very knowledgeable. You know what? Will is a very smart player; he's figured it out. That's why he's playing better."

Another possible reason: The cast alongside Pericak greatly improved with the Buffs' 2012 signing class. Nate Bonsu is back for his junior year in the best shape of his career, and freshmen Josh Tupou, Justin Solis and Tyler Henington all figure in Tuiasosopo's interior designs.

Said Tuiasosopo: "I feel good about those five."

Pericak (tackle) and Bonsu (nosetackle) opened with the No. 1 defense in the first major scrimmage of camp. But Tuiasosopo said Tupou "is really, really pushing Nate. Right now I have a lot of confidence in those three rotating in there. Nate came back in as good a shape as Will. Part of that is in the challenge we put to him in the spring: 'get your shoulder, your weight and your mind right.'"

Bonsu (6-1, 280) apparently paid attention to all three challenges and submitted a strong camp. But Tupou (6-3, 325) and Solis (6-3, 305) cast large shadows that Bonsu can't ignore. Tuiasosopo termed Tupou "special" and said Solis is "real stout. He's already low by stature and is hard to move. And he's beginning to figure it all out."

Flanking Tuiasosopo's interior guys are defensive ends Chidera Uzo-Diribe, a junior, and true sophomore Juda Parker. McGhee believes both will be solid on the edges.

Uzo-Diribe and Parker have gained about 20 pounds apiece since last season, now weighing nearly 255 each. And both contend the mandated weight gains have made them better. McGhee agrees: "I see a big difference in them. I told those guys last spring they needed to put on weight, but they were both kind of concerned it would affect their speed. I said, 'Not if you put it on right.'

"Malcolm (Blacken, director of speed, strength and conditioning) has done a great job of balancing their speed and strength.' The most amazing thing for them for them is that when they put pads on and come out here, they see they have more strength and leverage and didn't lose any of their speed."

Uzo-Diribe called his weight gain and accompanying weight-room improvement "a concentrated effort on my part and their (strength coaches) part. I knew I had to get stronger. It was one of the reasons I wasn't very effective against the run; I just wasn't strong. So I had to definitely improve my strength in the weight room to be able to hold my own."

After a break-in freshman season (he appeared in nine games), Parker said he now understands "what's expected of me. It took time to get in shape physically and mentally. I've conditioned myself for this and the transition has been a lot smoother. I know what I'm supposed to be doing; I know the big picture for this defense."

Parker's personal goals center on being a consistent contributor: "When people look at me they can be secure knowing I'm going to have my side of the ball," he said. "I'm going to make my tackles; I'm going to give this defense a solid starting defensive end."

Backing up Uzo-Diribe and Parker will be sophomore Kirk Poston and true freshmen John Stuart and Samson Kafovalu. McGhee called Poston his most improved player in August camp, adding Poston was "a little lighter than we wanted him coming back (250 listed), but he's strong. He's been most impressive through camp."

Stuart and Kafovalu, said McGhee, picked things up quickly but still have some "bad high school habits we have to get them out of. But they are guys who have to play."

For CU's returning defensive players, it was sometimes difficult not to gawk at the overall size of the incoming freshmen on their side of the ball.

Parker was impressed: "We're getting the 'size guys,' guys who are ready to come in and play," he said. "I know the younger guys right now have to get over the hump in the mental aspect - the same thing I faced last year . . . . Once we get them mentally right I think we'll be fast and have a solid defensive line."

THE INSIDE LOOK AT . . .

Defensive line

Coach: DT Mike Tuiasosopo, second season on CU staff; DE Kanavis McGhee, second season on CU staff.

Stat line: CU has lacked a preeminent QB sacker of late, but Hartigan came close with eight in 2011. Uzo-Diribe recorded 51/2 sacks last season and is expected to increase that total this fall. No other returning defensive lineman recorded a sack in 2011.

Bottom line: This is another position where CU's overall youth likely will be on display - very quickly. Pericak is a solid tackle and Uzo-Diribe and Parker can be forces at end, but they need help. Parker progressed nicely in his first season and must make more strides as a sophomore. The Buffs gave up 183.9 rushing yards a game last season (10th Pac-12, 89th NCAA) and need immediate help in stopping the run from those large D-line recruits like Tupou, Solis and Henington. A slimmed down, stronger Bonsu also should benefit the interior and Pericak is primed for a productive final season.